1. `Field of the Invention
This invention relates to a throttle control apparatus for motorcycles and similar vehicles, and more particularly, to a cam lever motorcycle throttle control which is mounted in the vehicle throttle housing and is designed to bias the throttle cable drum and the throttle handle or grip attached to the cable drum in a selected throttle position or setting as the motorcycle is operated. The conventional motorcycle twist grip throttle is designed to control the speed of the engine by means of a cable or cables enclosed in a cooperating conduit or conduits, one end of which cable is attached to the engine carburetor linkage and the other end to a cable drum which cooperates with a twist grip handle or throttle mounted on the handle bars of the vehicle. The throttle handle is biased toward a preselected idle speed by the spring mounted on the carburetor end of the cable. As the throttle is twisted in the counter-clockwise direction (as viewed by the rider) against the bias of the spring the cable is wound on the cable drum and is displaced inside the cable conduit, and the engine is caused to operate at a higher rpm. In many cases, and particularly on long trips where a relatively constant throttle setting is desired in order to maintain a particular speed of travel, it is desirable to maintain the throttle in position at a selected carburetor setting. It is also desirable to maintain this selected speed setting by mechanical means in order to rest the muscles of the hand and arm. In addition to functioning as a throttle immobilizing device, the mechanical mechanism employed to maintain a selected throttle setting must also be easily susceptible of manual override in the event of emergency, it should not interfere with the carburetor cable spring in returning the throttle to idle speed position when the device is positioned in the "off" configuration, and it must be simply designed and easy to manipulate, as well as conveniently located on or near the handle bars of the vehicle.
2. Description of the Prior Art
Since hand grip throttles on motorcycles and similar vehicles are spring-biased to return to the idle speed condition when the operator's hand is released, most of the prior art devices designed to maintain a specified throttle speed setting are designed to counteract the bias of this spring. One such device is disclosed in U.S. Pat. No. 4,060,008 to Jerome Wilkinson, which device includes a pair of elongated members hinged at one end and having arcuate surfaces adapted to contact the throttle control member or grip, with an O-ring or other biasing member such as a rubber band attached to the opposite end to hold the throttle grip at a selected speed setting. Another throttle control device for motorcycles is disclosed in U.S. Pat. No. 3,982,446 to Andrew Van Dyken, which device includes a slip ring slidably fitted around the outer periphery of a collar, the latter of which is fastened to the rotatable hand grip throttle control. The slip ring is designed to selectively tighten around the collar and throttle grip to maintain the throttle grip at a selected speed setting according to the desires of the rider. Another throttle control device for motorcycles is disclosed in U.S. Pat. No. 4,137,793 to William E. Sowell, which device includes a clamping arrangement mounted over the rotatable sleeve of a throttle control device in the motorcycle, and provided with a tab that engages conventional equipment mounted on the handle bars to selectively prevent rotation of the throttle at certain speed settings selected by the rider.
Many of the prior art throttle control devices for motorcycles are disadvantageous, in that they are cumbersome and unwieldy, and sometimes prove to be difficult to mount on the handle bars and throttle mechanism assembly of the vehicle. Furthermore, some of these prior art mechanisms do not easily allow the throttle to return to the original, preset idle position when they are released, a factor which can be dangerous in the operation of such speed control devices. Such devices must perform basically three functions in order to be effective in maintaining a safe engine throttle setting during operation of a motorcycle or similar vehicle; first, the device must be simple, easy to manipulate and control, and it must operate in a positive manner to hold a desired engine throttle setting. Secondly, the throttle control mechanism must be quickly and easily susceptible of manual override in the event of an emergency without the necessity of tripping the engaging and disengaging mechanism to achieve the override condition. Third, the device should operate to completely disengage from contact with the throttle cable drum or sleeve when disengaged to allow the throttle to return to the idle position by operation of the carburetor spring.
Accordingly, it is an object of this invention to provide a new and improved throttle control which is characterized by a cam lever pivotally mounted in a threaded cam lever body, which body is threadably inserted in a tapped aperture in the throttle housing of a motorcycle or similar vehicle, with a spring-biased cam lever plunger in contact with the motorcycle housing cable drum attached to the vehicle throttle grip, to selectively bias the cable drum and grip at a selected desired throttle setting by initially rotating the throttle grip to a desired engine speed setting and vehicle speed, and subsequently manipulating the cam lever.
Another object of this invention is to provide a new and improved cam lever-actuated throttle control device for motorcycles and similar vehicles, which device performs the function of positively maintaining substantially any desired engine throttle position by simple manipulation of the cam lever, and yet facilitates a quick and easy manual override without the necessity of disengaging the device in an emergency situation.
A still further object of the invention is to provide a motorcycle and similar vehicle throttle control device which includes a cam lever and a cooperating threaded cam lever body, which body is threadably inserted in the throttle housing of a motorcycle with the spring-biased cam lever plunger in selective contact with the vehicle cable drum to effect positive, yet quickly releasable speed control of the motorcycle.
Yet another object of this invention is to provide a new and improved cam lever-operated throttle control device for motorcycles and similar vehicles, which device can be quickly and easily installed on the vehicle by drilling a hole in the motorcycle throttle housing, tapping the hole to receive the threads of the cam lever body, and threadably attaching the cam lever body and cam lever to the throttle housing for selective engagement of the internally spring-biased cam lever plunger with the rotatable cable drum attached to the vehicle throttle grip to achieve a positive, yet easily overridden speed control of the motorcycle.
Still another object of the invention is to provide a new and improved throttle control for motorcycles which includes a cam lever mechanism having a spring biased plunger adapted to contact the motorcycle cable drum to immobilize the drum at a selected carburetor speed setting and withdraw from the cable drum to allow the throttle to respond to the throttle spring and return to idle speed.